Your smartwatch, your earbuds, your fitness tracker, maybe one day your glucose monitor or pacemaker — they all talk to each other by shouting. Bluetooth and similar radio technologies broadcast electromagnetic waves in every direction, and those waves don’t stop at your skin. According to Purdue University researchers, a typical Bluetooth signal can be picked up within roughly a 10-meter radius of your body. That’s convenient for pairing headphones, but it also means anyone with the right antenna in the same room can capture the raw signals of your personal devices — including medical ones.